update indigo
update indigo

* submodules/infra b521bed...6898254 (4):
  > Merge into master from pull request #15: AIM: add a debug-only assert macro (https://github.com/floodlight/infra/pull/15)
  > Merge into master from pull request #14: clean up clang static analysis warnings (https://github.com/floodlight/infra/pull/14)
  > Merge into master from pull request #13: AIM: do not fail if allocating zero bytes returns NULL (https://github.com/floodlight/infra/pull/13)
  > Merge into master from pull request #12: AIM: add integer log2 utilities (https://github.com/floodlight/infra/pull/12)

harfly/indigo,harfly/indigo,harfly/indigo,harfly/indigo